1. Field of the Invention
The present invention relates to novel pyrrolizidine compounds, salts thereof, a process for the preparation of same as well as pharmaceutical agents comprising same. Each of the compounds and salts shows an anti-ulcer activity and more particularly, against gastric ulcer.
2. Related Arts
Pharmaceutical agents for curing gastric ulcer can generally be classified into those suppressing offensive factors and those strengthening defensive factors. Among them, the former has greatly been developed but on the latter, it is fact that a development thereof makes slow progress and a study thereon now reaches to find a clue for dissolving the matter.
It has been a well known fact that the gastric juice as the offensive factor plays an important role on the gastric ulcer, in view of developmental pathology thereon and thus a suppression of its digestion power has been made as a main target for curing the gastric ulcer. Therefore, hitherto, the suppression of digestive power of the gastric juice, according to an antacid and inhibition of gastric secretion by mainly an agent having anticholine action have been employed as main curing measures. However, the former has a disadvantage in that an effective acting period of time is short and while the latter has also a disadvantage in that the agent may cause side effects of corediastasis, an exaggeration of glaucoma, tachycardia and the like depending on suppression of muscarinic receptor.
In recent years, antagonistic agents to a receptor of parietal cell have appeared as a new type anti-ulcer. Such agents have been watched with a great interest, since those are characterized by having a prolonging action on inhibition of gastric secreti in the stomach and show an actionof promoting a cure of ulcer, which is unique in comparison with and can not be found in the anti-ulcer agents which had been known at that time.
As exemplar antagonistic agents to the receptor of parietal cell Cimetidine of that to histaminic II receptor and Pirenzepine of a selective antagonistic agent to muscarinic receptor may be listed. It has been said those have little side effects in degree but the cimetidine have side effects of forming a perforation in ulcer and strengthening a delayed hypersensitive reaction and the pirenzepine shows side reactions due to supression of muscarinic receptor, although those are somewhat weak.